The principal objective of the Geisinger Clinical Oncology Program is to enroll maximal numbers of patients into NCI-approved cancer prevention, cancer control and cancer treatment clinical trials, thus bringing research-quality care to a large rural population of Pennsylvania. The Geisinger health care system serves more than 2.1 million Pennsylvanians across 31 primarily rural counties, from the state's northeastern corner to its midpoint. It is based on a 500-physician multispecialty group practice in 45 sites, anchored by a 577-bed tertiary care medical center in Danville--Geisinger Medical Center. This proposal will incorporate the multispecialty clinical and research facilities that are already in place with a new affiliate at the Geisinger Wyoming Valley Medical Center, a 230 bed secondary care referral hospital, with a 100 physician Geisinger group practice and a newly constructed cancer center on site. In addition, the Oncology Program will take advantage of the largest HMO in our region--the Geisinger Health Plan--with its 140,000 members, to enroll large numbers of normal subjects on cancer prevention trials. Geisinger continues to offer special advantages for continuation of the CCOP program: 1. Large cancer patient population for treatment/control studies. 2. Large population served generally, with research access to primary care practices and "normal" populations (1.198,225 clinic visits in 1992). 3. Stable, experience CCOP staff with a 10 year record of successful accrual to NCI treatment/control trials, successful relations with cooperative groups and consistently superb data quality. 4. Excellent patient record system, with unit charts, system-wide computerized lab, Computerized cancer registry which includes Geisinger (Danville) and GWV hospitals. 5. Fulltime, salaried multispecialty physician staff, able to provide all needed cancer treatment services under one roof both at Danville and GWV. 6. Successful competition to be a study center for the important Prostate Cancer Prevention Trial (PCPT), which starts October, 1993. 7. Strong institutional commitment to clinical trial research in cancer, with willingness to co-sponsor the costs of this research along with the NCI, despite increasingly tight financial times for all health care institutions. Geisinger openly recognizes this as a primary mission, not just a marketing tool. The proposal retains NCCTG as our primary research base; includes ECOG and CCG bases also.